This invention relates to apparatus and methods for the aeration of cesspools and more particularly to apparatus and methods for converting a static anaerobic operating cesspool system into a dynamic, aerobic waste disposal system.
In most if not all urban and in many suburban areas of this country, liquid wastes are conveyed for disposal through networks of sewage pipes. However, in many communities involving millions of homes and places of businesses, individual cesspools are still relied upon for the ultimate disposal of such wastes. A cesspool, as understood in the art, is a container planted usually beneath the surface of the ground, open on the bottom and frequently having openings in the side walls. Liquid waste material is discharged into the container, with solid material settling on the bottom and the liquid percolating down through the solid material collected on the bottom and some liquid seeping out through the side walls. A cesspool is effectively dead when the collected sludge on the bottom and the side walls is so dense that inflow exceeds outflow of the liquid and cleaning of the pool is incapable of altering that relationship. Anaerobic bacterial action breaks down the digestible solid materials present thereby, in theory at least, extending the life of the cesspool.
In practice, however, the useful life of a cesspool is shortened considerably by what actually occurs. Anaerobic bacterial action is inefficient and appears to be relatively ineffective in digesting much of the materials which should be digested, and it is possible that some of the waste materials themselves, such as detergents and other cleaning materials, may inhibit such action. Furthermore, the operation of the cesspool itself creates conditions which reduce the percolation rate of the water with the result that very often and possibly in most cases, the pool becomes filled with liquid long before it becomes filled with solid material. This results in cesspool overflow and backup problems.
The conditions in a cesspool which reduce the percolation rate and cause the problems described above involve the tendency of the solid and semi-solid material settling out of the liquid waste to pack on the bottom in such a way as to interfere with the flow of liquid through it. The layer of this material gets thicker as it builds up and packs down under its weight. Some of the smaller and finer parts of the digested sludge intermix between the grains of sand and gravel forming the bed for the pool and this increases the density of this underlying bed thereafter further restricting draining of the liquid. Constant flow of the liquid downwardly through the sludge and gravel beneath the bottom of the pool enhances packing of the solid materials which over a period of time reduces the rate of percolation and eventually leads to cesspool overflow and backup before being filled with solid material as described above.
This problem has long been recognized and there are certain techniques in current use to cope with the situation. When a cesspool becomes filled, a suction tube may be dropped into it and the liquid removed. Also, solid material can be agitated and removed along with the liquid. Under some conditions, workers can physically penetrate the pool with tools to scrape and remove the solid materials. These procedures are generally expensive and have to be repeated at frequent intervals because the underlying conditions which inhibit drainage are not rectified, and the pool fills up rapidly with the waste liquid being discharged into it.
Another technique frequently employed to drain a pool filled with liquid is to dump large amounts of concentrated sulfuric acid through the waste line. This is quite effective when first used but subsequent treatments can result in damage to the structure of the cesspool, and repeated uses are found to become less effective. In addition, the discharge of large amounts of such acids into the ground water is frowned upon by many environmentalists. Because such acids are heavy and sink rapidly to the bottom of the pool, this material will have no effect on an overflow pool which is in common use and required by many building authorities.
Elaborate arrangements for dealing with liquid waste products are shown in U.S. Pat. Nos. 1,398,394, 3,168,595, 3,828,933 and 4,376,702. These systems are relatively complex and do not appear to be able to solve the problems described above.